Science Q

[Rich H]

Well, I have asked my science teacher ( she doesn't seem to know ) and have tried looking on the internet, so I wanted to know if any of you guys know.
Well, in a nuclear reactor, power is created by neutrons hitting and breaking the Uranium, splitting it into smaller parts, called Nuclear Fission. And this leads onto a chain reaction.
But where do they get the neutrons from to fire at the Uranium? And how do they control the neutrons?

[expat]

You mean to say Wiki can't provide an answer :-?

Matt

[Sir_Crashalot]

[science mode]All fissionable and fissile isotopes undergo a small amount of spontaneous fission which releases a few free neutrons into any sample of nuclear fuel. Such neutrons would escape rapidly from the fuel and become a free neutron, with a half-life of about 15 minutes before they decayed to protons and beta particles. However, neutrons almost invariably impact and are absorbed by other nuclei in the vicinity long before this happens (newly-created fission neutrons are moving at about 7% of the speed of light, and even moderated neutrons are moving at about 8 times the speed of sound). Some neutrons will impact fuel nuclei and induce further fissions, releasing yet more neutrons. If enough nuclear fuel is assembled into one place, or if the escaping neutrons are sufficiently contained, then these freshly generated neutrons outnumber the neutrons that escape from the assembly, and a sustained nuclear chain reaction will take place.[/science mode]

Crash (professor in copy/paste techniques)

[Rich H]

Thanks! I have an enquiring mind 

[Mictheslik]

Neutrons can be collected in a variety of ways - http://en.wikipedia.org/wiki/Neutron_source

I'd imagine those used in nuclear reactors are a result of Spontaneous fission.

To control the process they use control rods that essentially absorb free neutrons and can be raised and lowered by technicians when more or less energy is needed (to create fewer or more collisions)

EDIT: I see Carlo beat me to it...had this reply up in the background for 20 minutes

.mic

[a1]

What they said...

Beat me to it.

[SubZer0]

...

42

[H]

...42

Is that above or below, zero?

8-)